Question: Simplify. Rewrite the expression in the form $5^n$. $(5^{-8})(5^{-10})=$
Recall that $x^n\cdot x^m=x^{n+m}$. $\begin{aligned} (5^{-8})(5^{-10})&=5^{(-8)+(-10)} \\\\ &= 5^{-8-10} \\\\ &= 5^{-18} \end{aligned}$